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US4673465A
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Separation of m-xylene from o-xylene by extractive distillation with polychloro compounds
Assignee: Individual
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Filing: 1986-04-21
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Granted: 1987-06-16
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Expires: 2006-04-21
Abstract
Abstract m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is a mixture polychloro aromatic compounds. Typical examples of effective agents are 2,3,4,6-tetrachlorophenol and p-dichlorobenzene; dimethyltetrachloroterephthalate, 2,3,4,6-tetrachlorophenol and 1,2,4,5-tetrachlorobenzene; 2,4,5-trichlorophenol, benzene hexachloride, o-dichlorobenzene and dioctyl phthalate.
Inventors
- 👤 Lloyd Berg
- 👤 An-I Yeh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:32
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/04; C07C7/05; C07C7/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
77 words
A method for recovering m-xylene from a mixture of m-xylene and o-xylene which comprises distilling a mixture of m-xylene and o-xylene in a rectification column in the presence of about one part of an extractive agent per part of m-xylene-o-xylene mixture, recovering m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot, the extractive agent comprises a mixture of aromatic chloro compounds at least one of which contains at least three chlorine atoms.
Claim 2
Independent Claim
77 words
A method for recovering m-xylene from a mixture of m-xylene and o-xylene which comprises distilling a mixture of m-xylene and o-xylene in a rectification column in the presence of about one part of an extractive agent per part of m-xylene-o-xylene mixture, recovering m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot, the extractive agent comprises a mixture of aromatic chloro compounds at least one of which contains at least three chlorine atoms.
Claim 3
Dependent Claim
45 words
The method of claim 1 in which the extractive agent comprises a mixture of dimethyltetrachloroterephthalate and at least one material from the group consisting of o-dichlorotoluene, 2-chlorotoluene, 2,4-dichlorotoluene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, benzene hexachloride, hexachlorobenzene, polychlorobenzene, trichloropropane, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol, perchloropentacyclohexane, tetrachlorophthalic anhydride and polychlorobiphenyl.
Claim 4
Dependent Claim
37 words
The method of claim 1 in which the extractive agent comprises a mixture of tetrachlorophthalic anhydride and at least one material from the group consisting of o-dichlorobenzene, p-dichlorobenzene, 1,2,4-trichlorobenzene, trichloropropane, polychlorobenzene, polychlorobiphenyl, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol.
Claim 5
Dependent Claim
31 words
The method of claim 1 in which the extractive agent comprises a mixture of 2,4,5-trichlorophenol and at least one material from the group consisting of o-dichlorobenzene, benzene hexachloride, polychlorobiphenyl and 1,1,1-trichloro-2,2bis(p-chlorophenyl)ethane.
Claim 6
Dependent Claim
30 words
The method of claim 1 in which the extractive agent comprises a mixture of 2,4,6-trichlorophenol and at least one material from the group consisting of 1,2,4-trichlorobenzene, benzene hexachloride and 1,2,4,5-tetrachlorobenzene.
Claim 7
Dependent Claim
34 words
The method of claim 1 in which the extractive agent comprises a mixture of 2,3,4,6 tetrachlorophenol and at least one material from the group consisting of o-dichlorobenzene, p-dichlorobenzene, 2,4-dichlorotoluene, 1,2,3-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, polychlorobenzene and trichloropropane.
Claim 8
Dependent Claim
19 words
The method of claim 1 in which the extractive agent comprises a mixture of 1,2,4-trichlorobenzene, o-dichlorotoluene and dioctyl phthalate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-15 | 1990-12-15 | 1991-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-15 | 1994-12-15 | 1995-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-15 | 1998-12-15 | 1999-06-16 | $7700.00 | Window Closed / Lapsed |